Question

Explain the term parallax in the context of reading a meniscus and how you would avoid any error that might be introduced by parallax?

Answer 1

Parallax is the displacement of an object between two lines of sight, which can be measured in angles, reading the meniscus (the C-shaped disc that cushions the knee), to avoid any error in reading you must hold the meniscus at a 0/180 degree angle to the eye, taking measurement from the base of the meniscus.